The United Nations Under-Secretary-General for Humanitarian Affairs and Emergency Relief Coordinator Martin Griffiths is heading to Türkiye to attend a high-level meeting with Turkish, Russian and Ukrainian officials for an extension of the Black Sea grain deal on May 10-11.

U.N. deputy spokesperson Farhan Haq told reporters Tuesday that Grifftihs left Jeddah, Saudi Arabia for Istanbul.

''We do expect some high-level meeting to happen this week,'' he said.

The Turkish National Defense Ministry announced Tuesday that Türkiye, Russia, Ukraine, and the U.N. will hold talks on the Black Sea grain deal in Istanbul on May 10-11 as the Russian deadline nears.

The deal is set to expire on May 18.

Russia wants obstacles to exports of its fertilizer to be removed for it to agree to another extension of the grain deal which was signed in Istanbul last July among the four parties.

Meanwhile, inspections of vessels resumed Tuesday of outbound vessels, said Haq.

''There have been at least two inspections carried out so far today,'' he added.

Türkiye announced on Tuesday the Black Sea grain corridor has been made operational again thanks to the country's efforts after Ukraine claimed Russia effectively stopped the landmark deal by refusing to register incoming vessels.